1. Field of the Invention
The present invention relates to tools that are used to turn fasteners having polygonal sided sockets. In particular, the present invention relates to tools having a rounded head, thereby having the capability of turning such fasteners in a non-coaxial relationship.
2. Description of the Prior Art
The previously known prior art contains several tools that have a rounded or a circular head used to turn fasteners that have polygonal sockets or recesses. The purpose of the rounded head is to provide the capability of turning the fastener in an angular relationship with respect to the fastener's axis. This capability is important where the fastener is located in a hard to reach place. In this situation. it is necessary to insert the tool and turn it through a partial turn, then withdraw the tool and reinsert it into the socket, and go through another partial turn, and so on, wasting both time and effort.
The prior art, in attempting to solve this problem, has approached several limitations. The first limitation is the angle with respect to the axis of the fastener in which the tool can be used to turn the fastener without binding the fastener. British Pat. No. 548,615 shows a hex wrench with this limitation. FIG. 1 displays at how small of an angle the hex wrench is able to engage the socket without binding. This is due to the nature of the curvature of the ball head. In an effort to enable even this small an angle of tilting to take place, the neck is made relatively small in diameter. One advantage of using hex wrenches is their ability to withstand great angular forces without twisting. In forming the neck portion, the inherent strength of the wrench can be compromised if the neck portion is made too small in diameter. Manufacturing a tool with a small neck diameter risks the chance of the head being twisted off under great force.
British Pat. No. 876,781 shows a tool in FIG. 1 that circumvents the problem of binding by providing a certain amount of play "between the ball-shaped head and the socket". This is evident from FIG. 2. This, however, tends to increase the chance of the edges of the ball becoming rounded when substantial forces are applied to the tool to cause the tool to slip with respect to the socket.
U.S. Pat. No. 3,940,946 shows a universal joint with a head portion larger than its shaft. This prevents the use of standard polygonal stock. In order to use standard polygonal stock, the head can be no larger than the shank or shaft. Furthermore, the sides of the head are not of uniform width. While this might be satisfactory with a universal joint where the head and socket can be matched, it would preclude the use of a head of this type as an element of a wrench where the wrench must be used with standard socket types of screw fasteners. Moreover, the patentee depends upon the use of an elastomeric material over the head to prevent binding in the socket.
U.S. Pat. No. 4,080,079 shows a universal joint in which the sides are arcuately curved with substantially the same radius as the radius of the ball portion. As will be pointed out later in the specification, this does not result in the maximum amount of tilting for a given shank size.